Service unit for vehicle air-conditioning systems and method for removing the coolant or a coolant/compressor oil mixture from a vehicle air-conditioning system

ABSTRACT

The invention relates to a service unit for vehicle air-conditioning systems, which is provided with an emptying and filling device for removing the coolant or a coolant/compressor oil mixture from a vehicle air-conditioning system and replenishing the vehicle air-conditioning system with coolant and optionally with compressor oil. The device can include at least one tank for coolant and a vacuum pump for generating a negative pressure in the vehicle air-conditioning system emptied of coolant or coolant/compressor oil mixture for a subsequent intake of coolant and optionally compressor oil into the vehicle air-conditioning system to be replenished. A chimney-like gas-collecting chamber having upper and lower openings can be arranged inside the service unit and is otherwise sealed off from the surrounding atmosphere.

FIELD OF THE INVENTION

The invention relates to a service unit for vehicle air-conditioningsystems having the features of the preamble of claim 1 and a method forremoving the coolant or a coolant/compressor oil mixture from a vehicleair-conditioning system having the features of the preamble of claim 10.

TECHNOLOGICAL BACKGROUND

A vehicle air-conditioning system to be maintained consistssubstantially of a generally oil-lubricated compressor, a condenser, anevaporator, and pipelines which form a closed coolant system betweenthese components. Furthermore, a dryer is generally provided, which canalso act as a collector or reservoir for coolant. Finally, two serviceconnections are incorporated in the coolant circuit for fluid exchange.The cold available at the evaporator in the vehicle is conducted away bya cold air blower and fed to the vehicle interior. The condensation heatof the condenser is conducted away by a warm air blower. Serviceconnection connectors on the vehicle air-conditioning system allowcoolant/compressor oil mixture to be drawn off or added at at least one,in particular the low-pressure (NP) service connection duringmaintenance. The vehicle air-conditioning systems differ from vehicletype to vehicle type and do not form the subject matter of the presentinvention.

Service units for vehicle air-conditioning systems serve among otherthings to drain the coolant circuit of a wide variety of vehicleair-conditioning systems from time to time and introduce a new coolantfilling during maintenance. In this case it is necessary to observeprecise quantities and coolant specifications. Moreover, in many caseslubricating oil for the compressor of the coolant circuit of the vehicleair-conditioning system must be removed and replenished. This also takesplace in quantities and specifications depending on the vehicle type andair-conditioning unit type. Some vehicle air-conditioning systems alsorequire an additive for the coolant circuit, which is likewise partiallyreplaced during maintenance. Usually, the compressor oil passes into thecoolant circuit and is circulated as well during operation of thevehicle air-conditioning system. Only very specific pairings of coolantand compressor oil are compatible with each other for this purpose. Inorder to be able to recover at least some of the coolant for reuse afterextraction of the coolant/compressor oil mixture, service units forvehicle air-conditioning systems usually also have a separator, withwhich coolant can be separated from the coolant/compressor oil mixturefor reuse. Used compressor oil and where necessary used additive isgenerally collected by the service unit in order to be discarded later.

WO 2007/085480 of the applicant discloses a service unit for vehicleair-conditioning systems according to the block diagram and FIG. 1. Thisshows the essential constituents of the generic service unit for avehicle air-conditioning system in solid lines and a vehicleair-conditioning system to be maintained in dashed lines. The latterconsists of an oil-lubricated compressor 1, a condenser 2, an evaporator3, and pipelines 4A-4C forming a closed coolant system between thesecomponents. Furthermore, a dryer 5 is provided, which can also act as acollector or reservoir for coolant. Finally, two service connections 6a/ 6 b are incorporated in the coolant circuit for fluid exchange. Thecold available at the evaporator 3 in the vehicle is conducted away by acold air blower 7 and fed to the vehicle interior. The condensation heatof the condenser 2 is conducted away by a warm air fan 8. Serviceconnection connectors 9A and 9B allow coolant/compressor oil mixture tobe drawn off and added at the service connections 6A, 6B duringmaintenance. The vehicle air-conditioning system labelled 10 overalldiffers from vehicle type to vehicle type and does not form the subjectmatter of the present invention.

A service unit, labelled 20 overall, for a vehicle air-conditioningsystem has flexible pressure hoses 11A, 11B for connecting the serviceunit 20 to the vehicle air-conditioning system 10 by means of theservice connection connectors 9A, 9B at the service connections 6A, 6B.An extraction pump 12 configured as a coolant compressor delivers usedcoolant/compressor oil mixture via the pressure hoses 11A and 11B andthe separator 14. The latter separates coolant from the extractedmixture by evaporation and feeds it to a coolant store 15 configured asa pressurised tank. Compressor oil/additive mixture separated off in theseparator 14 is collected in a replaceable used oil tank 15 and itsweight is detected by means of a weighing device 17A. An air-cooledcoolant condenser 15A is connected fixedly to the coolant store 15.Recycled coolant is thereby fed predominantly in liquid form to thecoolant store 15. The whole coolant store including the condenser restson a further weighing device 17B for detecting the coolant fed anddischarged and in store. After the extraction of the used mixture, avacuum pump 13 provides the underpressure, which is necessary forrefilling, in the circuit of the vehicle air-conditioning system andemits the extracted gas volume to the atmosphere.

A refilling system labelled 19 overall consists substantially ofreplaceable storage tanks 19D for compressor oil and 19C for additives,a control unit 19A with a valve block and control lines 19B, a remotedisplay 19E and metering and valve units 19F′ to 19F′″. The storagetanks 19C and 19D can preferably be weighed. Further weighing devices17C, 17D are used for this purpose.

DE 20 2008 003 123 U1 discloses a further service unit for vehicleair-conditioning systems of the applicant, in which the ability of thepreviously evacuated vehicle air-conditioning system to be refilled isimproved by a heat source, which is provided in the coolant storage tankand serves to increase the pressure of the coolant.

The still unpublished German Patent Application No. 10 2009 054 436.4 ofthe applicant, filed on 25 Nov. 2009, the disclosure content of which isincluded in the present patent application, discloses detecting thequantities of coolant initially present in the coolant circuit system ofthe vehicle air-conditioning system as precisely as possible duringmaintenance of vehicle air-conditioning systems, in order to improvediagnosis of the condition of the vehicle air-conditioning system. Tothis end, a service unit for vehicle air-conditioning systems having adrainage and filling device for extracting the coolant/compressor oilmixture from the coolant circuit system of a vehicle air-conditioningsystem and for refilling the vehicle air-conditioning system withcoolant and compressor oil, having a separation stage comprising atleast one separator, a coolant compressor and a coolant weighing device,and having a vacuum pump for draining the residues of the coolantcircuit system of the vehicle air-conditioning system is proposed, inwhich at least one pressure- and/or time-controlled switching valveblock is provided for the optional direct fluid connection of thecoolant circuit system to the separation stage and for the diversion ofthe flow connection from the coolant circuit system of the vehicleair-conditioning system via the vacuum pump to the separation stage.

PRESENTATION OF THE INVENTION

The invention is based on the object of being able to use inflammable orotherwise critical coolants, such as the coolant R-1234 yf, safely in ageneric service unit for vehicle air-conditioning systems. This objectis achieved by a service unit for vehicle air-conditioning systemshaving the features of claim 1 and a method having the features of claim10.

Accordingly, the invention provides for a chimney-like gas collectionchamber to be provided inside the service unit in a generic service unitfor vehicle air-conditioning systems. The chimney-like gas collectionchamber has an upper and a lower opening to the ambient atmosphere andis also sealed off from the ambient atmosphere. An active fan isprovided in such a manner that ambient air can flow through thechimney-like gas collection chamber from top to bottom. This means thatall the regions of the service unit which can come into contact with thegas of the coolant systematically or owing to leakages can befluid-connected to the chimney-like gas collection chamber and sealedoff from the remaining ambient atmosphere. Escaping coolant gas canthereby be kept away from unit parts which potentially form sparks.Other unit parts which are unavoidably fluid-connected to the ambientatmosphere are therefore sealed off from the chimney-like gas collectionchamber.

The active fan ensures that flow passes through the chimney-like gascollection chamber from top to bottom, for which ambient air is used.This means firstly that gas exchange also takes place in less accessibleregions of the chimney-like gas collection chamber. Secondly, it isthereby possible to accommodate certain electrical components in thechimney-like gas collection chamber without the risk of explosion,deflagration or inflammation in the atmosphere of the chimney-like gascollection chamber increasing. This is advantageous in particular ifcustomary vacuum pumps are used in the air-conditioning service unit,with which the electrical unit part of the vacuum pump can come intocontact with the gas to be evacuated. The active ventilation ensuresthat such gas constituents are conducted quickly outwards, so that morecomplex vacuum pump designs with complete separation of the electricalpart from the gas atmosphere are unnecessary. This active ventilationcan be supported further by additional second and/or third activeventilation systems.

If the atmosphere in the chimney-like gas collection chamber is heavieroverall than air, the active fan can remain switched off during stoppagephases or phases when the service unit is not in use, because electricalsparks are not produced in these phases and it is therefore sufficientif the heavier gases sink inside the chimney-like gas collection chamberand exit the latter to the environment through the lower opening.

If the active fan or at least its electrically supplied component groupsor where appropriate a unit controller are arranged outside theair-conditioning service unit or at least on the outer side thereof,potential ignition risks in the chimney-like gas collection chamberarising from the active fan itself can also be avoided.

The components to be used according to the invention which are mentionedabove, as well as those claimed and described in the exemplaryembodiments, are not subject to any special exceptional conditions interms of their size, shape, material and technical design, so theselection criteria known in the field of application can be used withoutrestriction.

Further details, features and advantages of the subject matter of theinvention can be found in the subclaims, and in the description of theassociated drawing and table below, in which an exemplary embodiment ofan air-conditioning service unit is shown by way of example.

BRIEF DESCRIPTION OF THE FIGURES

In the drawing,

FIG. 2 shows the service unit for vehicle air-conditioning systems invertical section (section along line I-I according to FIG. 3), and

FIG. 3 shows the same unit in vertical section shifted 90° (sectionalong line according to FIG. 2)

PRESENTATION OF AN EXEMPLARY EMBODIMENT

As can be seen in the sectional diagrams of FIGS. 2 and 3, thechimney-like gas collection chamber 110 is for the most part formed bythe unit walls 112, which are closed in on themselves, on the outersides of the unit, the unit cover 114 and a funnel-shaped bottom 118 ore.g. a perforated plate (not shown) situated at the lower end of theunit. As the active fan 120, a first electrical fan is docked from theoutside of the unit onto the upper opening 110A of the chimney-like gascollection chamber 110. The lower opening 110B of the chimney-like gascollection chamber 110 to the atmosphere is situated at the lower end ofthe funnel-shaped bottom 116, perforated plate or the like. One or aplurality of sealing walls 118 in the unit interior can seal off thechimney-like gas collection chamber 110 from holding chambers 122 foraccommodating storage tanks 124A, 124B, 124C for compressor oils,additives, used circuit liquid and/or the like, which remain accessiblefrom the outside of the unit. A fluid connection can however also existbetween at least one of the holding chambers 122 and the chimney-likegas collection chamber 110, if the at least one of the holding chambers122 is sealed off at its unit outer wall 112. The chimney-like gascollection chamber 110 is surrounded by an additional dashed line inFIGS. 2 and 3 by way of example and only for illustration purposes.

Inside the chimney-like gas collection chamber there are, in addition toa collection tank 126 for coolant, a compressor 128 and a condenser 130and a vacuum pump 132 with an electric motor 132A and compressor part132B, among other things. These unit parts and the rest of theair-conditioning unit 100 can interact in the manner corresponding tothe prior art shown in FIG. 1.

A second fan 134 can additionally be arranged in the region of a unitwall 112 in order to ventilate the electric motor 132A of the vacuumpump 132 additionally. An opening 134A of a unit side wall 112 throughwhich the fan is connected to the atmospheric air is provided for this.The additional air stream 134B produced by the second fan 134 flows downtogether with the air stream 1208 produced by the active fan 120 via thebottom opening 110B of the chimney-like gas collection chamber 110 as anaggregate air stream 140.

In order to ensure sufficient heat dissipation at the condenser 130, thelatter can be connected to the external atmosphere via a third fan 136.To this end, the fan 136 is fluid-connected via a further opening 138Ain the unit outer wall 112 and a ventilation duct 136C to the externalatmosphere. The chimney-like gas collection chamber 110 is therebysealed off from the external atmosphere. The air stream produced by thethird fan 136 also exits the service unit 100 with the aggregate airstream 114 via the lower opening 110B of the chimney-like gas collectionchamber [through] the unit bottom 116.

The third fan 136 and the electric motor of the vacuum pump and thecompressor 128 are preferably connected in such a manner that they canonly start up if the first fan 120 is in operation and the downward airstream in the chimney-like gas collection chamber 110 is consequentlyactive. The second and third fans support the active ventilation of thechimney-like gas collection chamber 110 and its protective function.

LIST OF REFERENCE SYMBOLS

1 Compressor

2 Evaporator

3 Condenser

4A-C Pipelines

5 Separator

8A/B Service connections

7 Cold air blower

8 Warm air blower

9A/B Service connection connectors

10 Vehicle air-conditioning system

11A/B Pressure hoses

12 Extraction pump

13 Vacuum pump

14 Separator

15 Coolant store

15A Coolant condenser

16 Used oil tank

17A-J Weighing devices

18 Unloading device

19 Refilling system

19A Control unit with valve block

19B Control lines

19C Storage tank

19D Storage tank

19E Remote display

19F′ Metering and valve unit

19F″ Metering and valve unit

19F′″ Metering and valve unit

20 Service unit

26A Low pressure manometer

26B High pressure manometer

100 Service unit

110 Gas collection chamber

110A Upper opening

110B Lower opening

112 Side walls

114 Unit cover

116 Bottom

118 Sealing wall

120 Active fan

122 Holding chamber

124A-C Storage tank

126 Coolant tank

128 Compressor

130 Condenser

132 Vacuum pump

132A Electric motor

132B Compressor

134 Second fan

134A Opening

134B Additional air stream

136 Third fan

136A Opening

136C Ventilation duct

140 Aggregate air stream

1. A service unit for vehicle air-conditioning systems, having adrainage device and a filling device for removing the coolant or acoolant/compressor oil mixture from a vehicle air-conditioning systemand for refilling the vehicle air-conditioning system with coolant andwhere necessary with compressor oil, having at least one tank (126) forcoolant and having a vacuum pump (132) for producing an underpressure inthe vehicle air-conditioning system which has been drained of coolant orcoolant/compressor oil mixture for a subsequent extraction of coolantand where necessary compressor oil in the vehicle air-conditioningsystem to be refilled, characterised in that a chimney-like gascollection chamber (110) having upper and lower openings (110A, 110B) isarranged inside the service unit (100) and is otherwise sealed off fromthe ambient atmosphere, and an active fan (120) is provided for the flowof ambient air through the chimney-like gas collection chamber (110)from top to bottom.
 2. The service unit according to claim 1,characterised in that at least the unit parts of the active fan (120)and/or any additional active fans to which electrical voltage is appliedand/or the control system thereof are arranged outside or on the outerside of the service unit.
 3. The service unit according to claim 1,characterised by an additional active fan (134) for loading a vacuumpump (132) arranged inside the chimney-like gas collection chamber (110)with ambient air.
 4. The service unit according to claim 1,characterised in that at least one, in particular a customary, vacuumpump (132) is used in the air-conditioning service unit, in which theelectrical unit part of the vacuum pump (132) comes into contact withthe gas to be evacuated.
 5. The service unit according to claim 1,characterised by an additional active fan (136) for loading a condenser(130) arranged inside the chimney-like gas collection chamber (110) withambient air.
 6. The service unit according to claim 1, characterised inthat the air streams of all the active fans can be conducted as anaggregate air stream (140) via a bottom exit opening (110B) of thechimney-like gas collection chamber (110).
 7. The service unit accordingto claim 1, characterised in that additional storage tanks (124A, 124B,124C) of the service unit are sealed off fluidically from thechimney-like gas collection chamber (110) by at least one sealing wall(118).
 8. The service unit according to claim 1, characterised in thatin particular all the regions of the service unit which come or can comeinto contact with the gas of the coolant systematically or owing toleakages are or can be fluid-connected to the chimney-like gascollection chamber and shut off from the remaining ambient atmosphere.9. The service unit according to claim 1, characterised in that anyfurther fans, the electric motor of any vacuum pump and/or a compressorare preferably connected in such a manner that they can generally onlystart up if the downward air stream in the chimney-like gas collectionchamber 110 is active.
 10. A method for removing the coolant or acoolant/compressor oil mixture from a vehicle air-conditioning systemand for refilling the vehicle air-conditioning system with coolant andwhere necessary with compressor oil by means of a service unit having atleast one tank for coolant and having a vacuum pump for producing anunderpressure in the vehicle air-conditioning system which has beendrained of coolant or coolant/compressor oil mixture for subsequentextraction of coolant and where necessary of compressor oil into thevehicle air-conditioning system to be refilled, characterised in that achimney-like gas collection chamber having upper and lower openings isprovided inside the service unit and is shut off from the remainingambient atmosphere, and ambient air flows through the chimney-like gascollection chamber from top to bottom, in particular by means of atleast one active fan.
 11. The method according to claim 10,characterised in that the at least one active fan for the chimney-likegas collection chamber remains switched off during stoppage phases orphases in which the service unit is not used, and the gases are left tosink downwards inside the chimney-like gas collection chamber, so thatthey exit the chimney-like gas collection chamber through the loweropening towards the ambient atmosphere.
 12. The method according toclaim 10, comprising a separation step for coolant/compressor oilmixture, characterised in that residues are drained from the coolantcircuit system of the vehicle air-conditioning system by means of avacuum pump, and the coolant circuit system is fluid-connected to aseparation stage for coolant/compressor oil mixture via the vacuum pumpfor the purpose of recovering coolant from the residue drainage of thecoolant circuit system.